Comey said of Sessions Thursday that "We also were aware of facts that I can't discuss in an open setting, that would make his continued engagement in a Russia-related investigation problematic".

But officials said Sessions's relationship with Trump has been strained since the attorney general recused himself from the Russian Federation probe in March.

This will be the first time Sessions has testified in Congress since he recused himself from the Justice Department's probe into Russian meddling in last year's election, and since the firing of FBI Director James Comey.

One aspect of the Comey hearing that was overwhelmed by the newsworthiness of his comments was his refusal to speak to the nature of Sessions' recusal from the Russian Federation investigation in an open hearing. Trump later said in an interview with NBC News's Lester Holt that he was going to fire Comey "regardless of the recommendation" and that he was thinking of the investigations into Russian involvement in the 2016 election when he made a decision to let the FBI director go.

The Justice Department says Sessions has requested Tuesday's committee hearing be open because he "believes it is important for the American people to hear the truth directly from him".

On "Fox & Friends" Monday, Conway noted Comey's testimony that Loretta Lynch, as President Barack Obama's attorney general, directed him to describe the FBI probe into Hillary Clinton's email practices as a "matter" and to avoid calling it an investigation.

Senate Majority Whip John Cornyn, an intelligence committee member, said senators were still deciding whether Sessions would be asked to testify in a classified briefing after the public hearing. On Saturday, he wrote the chairmen of both committees and said he was sending his deputy attorney general to testify in his place. Former FBI director James Comey brought Sessions' activities back under scrutiny last week, after reportedly telling the Senate in closed session that there was yet another meeting with Sergey Kislyak which Sessions failed to disclose.

Sessions' appearance before the intelligence committee is an indication of just how much the Russian Federation investigation has shaded his tenure. Mark R. Warner (D-Va.) announced that the hearing would be public.

Spokesman Spicer declined to say then that Sessions enjoyed Trump's confidence, though spokeswoman Sarah Huckabee Sanders said later in the week that the president had confidence "in all of his Cabinet". He is a good guy. That's what I think he's going to be considerably anxious about.

Of special interest will be Comey's assertion that he told Sessions after the meeting that he never again wanted to be left alone with the president.

After Trump had cleared the room, Comey said Chief of Staff "Reince Priebus leaned in through the door by the grandfather clock and I could see a group of people waiting behind him".

Ian Prior, a Justice Department spokesman, disputed that account and said that Sessions replied to Comey and said he "wanted to ensure that he and his Federal Bureau of Investigation staff were following proper communications protocol with the White House".

What is "problematic" about Sessions' relationship with Russian Federation?